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Relational graph location network for multi-view image localization

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系统工程与电子技术：英文版 2023年第2期34卷 460-468页

作者： YANG Yukun liu xiangdong School of Automation Beijing Institute of TechnologyBeijing 100081China

In multi-view image localization task,the features of the images captured from different views should be fused properly.This paper considers the classification-based image localization problem.We propose the relational graph location network(RGLN)to perform this task.In this network,we propose a heterogeneous graph construction approach for graph classification tasks,which aims to describe the location in a more appropriate way,thereby improving the expression ability of the location representation module.Experiments show that the expression ability of the proposed graph construction approach outperforms the compared methods by a large margin.In addition,the proposed localization method outperforms the compared localization methods by around 1.7%in terms of meter-level accuracy.

关键词： multi-view image localization graph construction heterogeneous graph graph neural network

Study on periodic orbits around the dipole segment model for dumbbell-shaped asteroids

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Science China(Technological Sciences) 2018年第6期61卷 819-829页

作者： ZHANG YongLong ZENG XiangYuan liu xiangdong School of Automation Beijing Institute of Technology

Equilibrium points and periodic orbits in irregular gravitational fields are significant for an understanding of dynamical behaviors around asteroids as well as deep space exploring missions. The dipole segment is a good alternative model to study qualitative dynamical properties near dumbbell-shaped asteroids. In this paper, the dipole segment model and its equilibrium points are simply introduced. The stability of the two triangular equilibrium points of the system is numerically examined. Next, periodic orbits are presented around the dipole segment model in two different cases, in which triangular equilibria are linearly stable and unstable,respectively. New types of periodic orbits are illustrated in detail, including their orbital shapes, periods and the Jacobi integral.The orbital stability, topological classification and bifurcations of these orbits are also analyzed with numerical continuations.

关键词：偶极子轨道周期模型流星学习哑铃 Jacobi

从系统功能语言学“层级-示例”矩阵关系看生态语言学

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北京第二外国语学院学报 2024年第1期46卷 130-141页

作者：刘向东天津科技大学外国语学院 300457

本文在系统功能语言学框架下探讨生态语言学的学科属性、研究路径、研究对象和内容。文章首先对生态语言学进行了简要综述与评论,然后以语言作为社会符号所处的“层级”与“示例”维度矩阵关系为基础,对生态语言学涉及的核心要素进行探... 详细信息

本文在系统功能语言学框架下探讨生态语言学的学科属性、研究路径、研究对象和内容。文章首先对生态语言学进行了简要综述与评论,然后以语言作为社会符号所处的“层级”与“示例”维度矩阵关系为基础,对生态语言学涉及的核心要素进行探讨。研究表明,“层级-示例”矩阵可为生态语言学各要素提供参照系;生态语言学是一种适用语言学,是系统功能语言学的适用性在广度和深度上的拓展。

关键词：生态语言学层级示例研究路径适用性

Trajectory reshaping based guidance with impact time and angle constraints

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Chinese Journal of Aeronautics 2016年第4期29卷 984-994页

作者： Zhao Yao Sheng Yongzhi liu xiangdong School of Automation Beijing Institute of Technology Key Laboratory for Intelligent Control and Decision of Complex Systems Beijing Institute of Technology

This study presents a novel impact time and angle constrained guidance law for homing missiles. The guidance law is first developed with the prior-assumption of a stationary target, which is followed by the practical extension to a maneuvering target scenario. To derive the closed-form guidance law, the trajectory reshaping technique is utilized and it results in defining a specific polynomial function with two unknown coefficients. These coefficients are determined to satisfy the impact time and angle constraints as well as the zero miss distance. Furthermore, the proposed guidance law has three additional guidance gains as design parameters which make it possible to adjust the guided trajectory according to the operational conditions and missile's capability.Numerical simulations are presented to validate the effectiveness of the proposed guidance law.

关键词： Guidance Homing missiles Impact angle Impact time Trajectory reshaping

Attitude coordination for spacecraft formation with multiple communication delays

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Chinese Journal of Aeronautics 2015年第2期28卷 527-534页

作者： Guo Yaohua Lu Pingli liu xiangdong School of Automation Beijing Institute of Technology

Communication delays are inherently present in information exchange between space- craft and have an effect on the control performance of spacecraft formation. In this work, attitude coordination control of spacecraft formation is addressed, which is in the presence of multiple communication delays between spacecraft. Virtual system-based approach is utilized in case that a constant reference attitude is available to only a part of the spacecraft. The feedback from the virtual systems to the spacecraft formation is introduced to maintain the formation. Using backstepping control method, input torque of each spacecraft is designed such that the attitude of each spacecraft converges asymptotically to the states of its corresponding virtual system. Furthermore, the back- stepping technique and the Lyapunov-Krasovskii method contribute to the control law design when the reference attitude is time-varying and can be obtained by each spacecraft. Finally, effectiveness of the proposed methodology is illustrated by the numerical simulations of a spacecraft formation.

关键词： Attitude coordination Backstepping Delay control systems Formation Lyapunov-Krasovskii

Sliding mode control based guidance law with impact angle constraint

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Chinese Journal of Aeronautics 2014年第1期27卷 145-152页

作者： Zhao Yao Sheng Yongzhi liu xiangdong School of Automation Beijing Institute of Technology Key Laboratory for Intelligent Control & Decision of Complex Systems Beijing Institute of Technology

The terminal guidance problem for an unpowered lifting reentry vehicle against a sta- tionary target is considered. In addition to attacking the target with high accuracy, the vehicle is also expected to achieve a desired impact angle. In this paper, a sliding mode control （SMC）-based guidance law is developed to satisfy the terminal angle constraint. Firstly, a specific sliding mode function is designed, and the terminal requirements can be achieved by enforcing both the sliding mode function and its derivative to zero at the end of the flight. Then, a backstepping approach is used to ensure the finite-time reaching phase of the sliding mode and the analytic expression of the control effort can be obtained. The trajectories generated by this method only depend on the initial and terminal conditions of the terminal phase and the instantaneous states of the vehicle. In order to test the performance of the proposed guidance law in practical application, numerical simulations are carried out by taking all the aerodynamic parameters into consideration. The effec- tiveness of the proposed guidance law is verified by the simulation results in various scenarios.

关键词： Backstepping Impact angle Sliding mode control Terminal guidance Unpowered lifting reentryvehicle

Finite-time sliding mode attitude control for a reentry vehicle with blended aerodynamic surfaces and a reaction control system

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Chinese Journal of Aeronautics 2014年第4期27卷 964-976页

作者： Geng Jie Sheng Yongzhi liu xiangdong Key Laboratory for Intelligent Control&Decision of Complex Systems Beijing Institute of Technology School of Automation Beijing Institute of Technology

This paper proposes a finite-time robust flight controller, targeting for a reentry vehicle with blended aerodynamic surfaces and a reaction control system（RCS）. Firstly, a novel finite-time attitude controller is pointed out with the introduction of a nonsingular finite-time sliding mode manifold. The attitude tracking errors are mathematically proved to converge to zero within finite time which can be estimated. In order to improve the performance, a second-order finite-time sliding mode controller is further developed to effectively alleviate chattering without any deterioration of robustness and accuracy. Moreover, an optimization control allocation algorithm, using linear programming and a pulse-width pulse-frequency（PWPF） modulator, is designed to allocate torque commands for all the aerodynamic surface deflections and on–off switching-states of RCS thrusters.Simulations are provided for the reentry vehicle considering uncertain parameters and external disturbances for practical purposes, and the results demonstrate the effectiveness and robustness of the attitude control system.

关键词： Chattering alleviation Control allocation Finite-time convergence Flight control systems Second-order sliding mode Singularity elimination Sliding mode control

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对置盐定理的再审视

财贸经济 2024年第3期45卷 144-163页

作者：王庚刘向东南京审计大学经济学院 211815 中国人民大学商学院 100872

置盐定理是西方理论界否定一般利润率趋向下降规律的集中代表。本文从置盐定理运用的转形体系和成本准则出发,在n部门经济下考察了转形体系切换时置盐定理的稳健性,以及考虑部门内竞争时定理中成本准则的适用性。研究发现,以价值转形B... 详细信息

置盐定理是西方理论界否定一般利润率趋向下降规律的集中代表。本文从置盐定理运用的转形体系和成本准则出发,在n部门经济下考察了转形体系切换时置盐定理的稳健性,以及考虑部门内竞争时定理中成本准则的适用性。研究发现,以价值转形B体系框架下建立的新生产价格体系为研究基准,即使实际工资不变,技术变革仍可能导致一般利润率下降,因此置盐定理的结论不具有稳健性。同时,在《资本论》第三卷着力阐述的部门内竞争确立市场价值的研究视角下,资本家的技术选择将遵循具有确切微观基础的、以部门平均技术为基准的“马克思的成本准则”,这一技术选择标准在部门中只有个别资本家掌握新技术时趋近于生产率准则,而只在全体资本家同步掌握新技术这一不现实的极端特殊情形下才退化为置盐的成本准则。总之,置盐定理不仅存在着稳健性问题,还将随着《资本论》研究传统下定理的基本假设不再适用而失效,围绕置盐定理展开的对一般利润率趋向下降规律的质疑与否定理应告一段落。

关键词：置盐定理转形体系成本准则一般利润率下降

DRIVING DIGITAL TRADE WITH DEPA

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China Report ASEAN 2023年第2期8卷 72-73页

作者： liu xiangdong the Macroeconomic Research Department at the China Center for International Economic Exchanges

Countries around the world now regard the digital economy as a key new driver of economic growth.Development of digital trade has become an important means to drive the growth of the digital economy as well as a new trend amid the evolution of international trade and related rules.Against this background,different countries and regions have established various versions of digital trade rules.

关键词： economy trend economic